UMLS:C0033036 - FACTA Search

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Query: UMLS:C0033036 (APC)
10,214 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Antigen presentation and T-cell activation are dynamic processes involving signaling molecules present in both APCs and T cells. Effective APC function and T-cell activation can be compromised by viral immune evasion strategies, including those of human immunodeficiency virus type 1 (HIV-1). In this study, we determined the effects of HIV-1 Vpr on one of the initial target of the virus, dendritic cells (DC), by investigating DC maturation, cytokine profiling, and CD8-specific T-cell stimulation function followed by a second signal. Vpr impaired the expression of CD80, CD83, and CD86 at the transcriptional level without altering normal cellular transcription. Cytokine profiling indicated that the presence of Vpr inhibited production of interleukin 12 (IL-12) and upregulated IL-10, whereas IL-6 and IL-1beta were unaltered. Furthermore, DC infected with HIV-1 vpr+ significantly reduced the activation of antigen-specific memory and recall cytotoxic-T-lymphocyte responses. Taken together, these results indicate that HIV-1 Vpr may in part be responsible for HIV-1 immune evasion by inhibiting the maturation of costimulatory molecules and cytokines essential for immune activation.
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PMID:Human immunodeficiency virus type 1 Vpr impairs dendritic cell maturation and T-cell activation: implications for viral immune escape. 1595 45

Gateways to Clinical Trials is a guide to the most recent clinical trials in current literature and congresses. The data in the following tables have been retrieved from the Clinical Trials Knowledge Area of Prous Science Integrity, the drug discovery and development portal, http://integrity.prous.com. This issue focuses on the following selection of drugs: Abiraterone acetate, acyline, adalimumab, adenosine triphosphate, AEE-788, AIDSVAX gp120 B/B, AK-602, alefacept, alemtuzumab, alendronic acid sodium salt, alicaforsen sodium, alprazolam, amdoxovir, AMG-162, aminolevulinic acid hydrochloride, aminolevulinic acid methyl ester, aminophylline hydrate, anakinra, anecortave acetate, anti-CTLA-4 MAb, APC-8015, aripiprazole, aspirin, atazanavir sulfate, atomoxetine hydrochloride, atorvastatin calcium, atrasentan, AVE-5883, AZD-2171; Betamethasone dipropionate, bevacizumab, bimatoprost, biphasic human insulin (prb), bortezomib, BR-A-657, BRL-55730, budesonide, busulfan; Calcipotriol, calcipotriol/betamethasone dipropionate, calcium folinate, capecitabine, capravirine, carmustine, caspofungin acetate, cefdinir, certolizumab pegol, CG-53135, chlorambucil, ciclesonide, ciclosporin, cisplatin, clofarabine, clopidogrel hydrogensulfate, clozapine, co-trimoxazole, CP-122721, creatine, CY-2301, cyclophosphamide, cypher, cytarabine, cytolin; D0401, darbepoetin alfa, darifenacin hydrobromide, DASB, desipramine hydrochloride, desloratadine, desvenlafaxine succinate, dexamethasone, didanosine, diquafosol tetrasodium, docetaxel, doxorubicin hydrochloride, drotrecogin alfa (activated), duloxetine hydrochloride, dutasteride; Ecallantide, efalizumab, efavirenz, eletriptan, emtricitabine, enfuvirtide, enoxaparin sodium, estramustine phosphate sodium, etanercept, ethinylestradiol, etonogestrel, etonogestrel/ethinylestradiol, etoposide, exenatide; Famciclovir, fampridine, febuxostat, filgrastim, fludarabine phosphate, fluocinolone acetonide, fluorouracil, fluticasone propionate, fluvastatin sodium, fondaparinux sodium; Gaboxadol, gamma-hydroxybutyrate sodium, gefitinib, gelclair, gemcitabine, gemfibrozil, glibenclamide, glyminox; Haloperidol, heparin sodium, HPV 16/HPV 18 vaccine, human insulin, human insulin; Icatibant, imatinib mesylate, indium 111 (111In) ibritumomab tiuxetan, infliximab, INKP-100, iodine (I131) tositumomab, IoGen, ipratropium bromide, ixabepilone; L-870810, lamivudine, lapatinib, laquinimod, latanoprost, levonorgestrel, licochalcone a, liposomal doxorubicin, lopinavir, lopinavir/ritonavir, lorazepam, lovastatin; Maraviroc, maribavir, matuzumab, MDL-100907, melphalan, methotrexate, methylprednisolone, mitomycin, mitoxantrone hydrochloride, MK-0431, MN-001, MRKAd5 HIV-1 gag/pol/nef, MRKAd5gag, MVA.HIVA, MVA-BN Nef, MVA-Muc1-IL-2, mycophenolate mofetil; Nelfinavir mesilate, nesiritide, NSC-330507; Olanzapine, olmesartan medoxomil, omalizumab, oral insulin, osanetant; PA-457, paclitaxel, paroxetine, paroxetine hydrochloride, PCK-3145, PEG-filgrastim, peginterferon alfa-2a, peginterferon alfa-2b, perillyl alcohol, pexelizumab, pimecrolimus, pitavastatin calcium, porfiromycin, prasterone, prasugrel, pravastatin sodium, prednisone, pregabalin, prinomastat, PRO-2000, propofol, prostate cancer vaccine; Rasagiline mesilate, rhBMP-2/ACS, rhBMP-2/BCP, rhC1, ribavirin, rilpivirine, ritonavir, rituximab, Ro-26-9228, rosuvastatin calcium, rosuvastatin sodium, rubitecan; Selodenoson, simvastatin, sirolimus, sitaxsentan sodium, sorafenib, SS(dsFv)-PE38, St. John's Wort extract, stavudine; Tacrolimus, tadalafil, tafenoquine succinate, talaglumetad, tanomastat, taxus, tegaserod maleate, telithromycin, tempol, tenofovir, tenofovir disoproxil fumarate, testosterone enanthate, TH-9507, thalidomide, tigecycline, timolol maleate, tiotropium bromide, tipifarnib, torcetrapib, trabectedin, travoprost, travoprost/timolol, treprostinil sodium; Valdecoxib, vardenafil hydrochloride hydrate, varenicline, VEGF-2 gene therapy, venlafaxine hydrochloride, vildagliptin, vincristine sulfate, voriconazole, VRX-496, VX-385; Warfarin sodium; Ximelagatran; Yttrium 90 (90Y) ibritumomab tiuxetan; Zanolimumab, zidovudine.
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PMID:Gateways to clinical trials. 1608 22

Antibodies to the CD4-binding site (CD4bs) of HIV-1 envelope gp120 have been shown to inhibit MHC class II presentation of this antigen, but the mechanism is not fully understood. To define the key determinants contributing to the inhibitory activity of these antibodies, a panel of anti-CD4bs monoclonal antibodies with different affinities was studied and compared to antibodies specific for the chemokine receptor-binding site or other gp120 regions. Anti-CD4bs antibodies that completely obstruct gp120 presentation exhibit three common properties: relatively high affinity for gp120, acid-stable interaction with gp120, and the capacity to slow the kinetics of gp120 proteolytic processing. None of these antibodies prevents gp120 internalization into APC. Notably, the broadly virus-neutralizing anti-CD4bs IgG1b12 does not block gp120 presentation as strongly, because although IgG1b12 has a relatively high affinity, it dissociates from gp120 more readily at acidic pH and only moderately retards gp120 proteolysis. Other anti-gp120 antibodies, regardless of their affinities, do not affect gp120 presentation. Hence, high-affinity anti-CD4bs antibodies that do not dissociate from gp120 at endolysosomal pH obstruct gp120 processing and prevent MHC class II presentation of this antigen. The presence of such antibodies could contribute to the dearth of anti-gp120 T helper responses in chronically HIV-1-infected patients.
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PMID:Characterization of antibodies that inhibit HIV gp120 antigen processing and presentation. 1610 69

We show in this study that acute exposure of PBMCs derived from HIV-infected subjects to IL-13 results in increased recall T cell lymphoproliferative responses against HIV-1 p24 (n = 30, p < 0.0001) and other recall Ags (influenza, n = 43, p < 0.0001; purified protein derivative tuberculin, n = 6, p = 0.0299). This effect is due to a mechanism that acutely targets APC function in the adherent monocyte subset, as shown by the expansion of CD4(+) T cell responses following coculture of IL-13-treated enriched CD14(+) monocytes with donor-matched enriched CD4(+) T cells and Ag. Exposure to IL-13 over 18-72 h resulted in a significant enhancement of monocyte endocytosis (n = 11, p = 0.0005), CD86 expression (n = 12, p = 0.001), and a significant decrease in spontaneous apoptosis (n = 8, p = 0.008). Moreover, IL-13 exposure induced a significant decrease of significantly elevated constitutive levels of PBMC-secreted TNF-alpha (n = 14, p < 0.001) and IL-10 (n = 29, p < 0.001) within 18 h of exposure ex vivo, also reflected by decreased gene expression in the adherent cell population. Our data show that IL-13 is able to acutely enhance the function of the CD14(+) cell subset toward supporting Ag-specific cell-mediated responses in chronic HIV-1 infection.
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PMID:IL-13 acutely augments HIV-specific and recall responses from HIV-1-infected subjects in vitro by modulating monocytes. 1621 Jun 62

We have previously reported that immunization of the severe combined immunodeficiency (SCID) mice reconstituted with human peripheral blood mononuclear cells (PBMC) (hu-PBL-SCID mice) with inactivated human immunodeficiency virus type-1 (HIV-1)-pulsed-autologous dendritic cells (HIV-DC) elicits HIV-1-reactive CD4(+) T cells that produce an as yet to be defined novel soluble factor in vitro with anti-viral properties against CCR5 tropic (R5) HIV-1 infection. These findings led us to perform studies designed to identify the lineage of the cell that synthesizes such a factor in vivo and define the epitopes of HIV-1 protein that have specificity for the induction of such anti-viral factor. Results of our studies show that this property is a function of CD4(+) but not CD8(+) T cells. Human CD4(+) T cells were thus recovered from the HIV-DC-immunized hu-PBL-SCID mice and were re-stimulated in vitro by co-culture for 2 days with autologous adherent PBMC as antigen presenting cells, APC previously pulsed with inactivated HIV in IL-2-containing medium to expand HIV-1-reactive CD4(+) T cells. Aliquots of these re-stimulated CD4(+) T cells were then co-cultured with similar APC's that were previously pulsed with 10 microg/ml of a panel of HIV peptides for an additional 2 days, and their culture supernatants were examined for the production of both the R5 HIV-1 suppression factor and IFN-gamma. The data presented herein show that the HIV-1 primed CD4(+) T cells produced the R5 suppression factor in response to a wide variety of HIV-1 gag, env, pol, nef or vif peptides, depending on the donor of the CD4(+) T cells. Simultaneous production of human interferon (IFN)-gamma was observed in some cases. These results indicate that human CD4(+) T cells in PBMC of HIV-1 naive donors have a wide variety of HIV-1 epitope-specific CD4(+) T cell precursors that are capable of producing the R5 HIV-1 suppression factor upon DC-based vaccination with whole inactivated HIV-1.
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PMID:Identification of HIV-1 epitopes that induce the synthesis of a R5 HIV-1 suppression factor by human CD4+ T cells isolated from HIV-1 immunized hu-PBL SCID mice. 1658 8

CD4 is a coreceptor for binding of T cells to APC and the primary receptor for HIV. The disulfide bond in the second extracellular domain (D2) of CD4 is reduced on the cell surface, which leads to formation of disulfide-linked homodimers. A large conformational change must take place in D2 to allow for formation of the disulfide-linked dimer. Domain swapping of D2 is the most likely candidate for the conformational change leading to formation of two disulfide-bonds between Cys130 in one monomer and Cys159 in the other one. Mild reduction of the extracellular part of CD4 resulted in formation of disulfide-linked dimers, which supports the domain-swapped model. The functional significance of dimer formation for coreceptor function was tested using cells expressing wild-type or disulfide-bond mutant CD4. Eliminating the D2 disulfide bond markedly impaired CD4's coreceptor function. Modeling of the complex of the TCR and domain-swapped CD4 dimer bound to class II MHC and Ag supports the domain-swapped dimer as the immune coreceptor. The known involvement of D4 residues Lys318 and Gln344 in dimer formation is also accommodated by this model. These findings imply that disulfide-linked dimeric CD4 is the preferred coreceptor for binding to APC.
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PMID:Evidence for a domain-swapped CD4 dimer as the coreceptor for binding to class II MHC. 1670 47

CTLs can acquire MHC class I-peptide complexes from their target cells, whereas CD4(+) T cells obtain MHC class II-peptide complexes from APCs in a TCR-specific manner. As a consequence, Ag-specific CTL can kill each other (fratricide) or CD4(+) T cells become APCs themselves. The purpose of the acquisition is not fully understood and may be either inhibition or prolongation of an immunological response. In this study, we demonstrate that human CD4(+) Th cells are able to capture membrane fragments from APC during the process of immunological synapse formation. The fragments contain not only MHC class II-peptide complexes but also MHC class I-peptide complexes, rendering these cells susceptible to CTL killing in an Ag-specific manner. The control of CD4(+) Th cells by Ag-specific CTL, therefore, maybe another mechanism to regulate CD4(+) T cell expansion in normal immune responses or cause immunopathology during the course of viral infections such as HIV.
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PMID:CTLs target Th cells that acquire bystander MHC class I-peptide complex from APCs. 1761 73

CD8(+) cytotoxic T lymphocytes (CTL) play an important role in controlling virus replication in HIV- and SIV-infected humans and monkeys, respectively. Three well-studied SIV CTL determinants are the two Mamu A()01-restricted epitopes Gag CM9 and Tat SL8, and the Mamu B()17-restricted epitope Nef IW9. Point mutations leading to amino acid replacements in these epitopes have been reported to mediate SIV escape from CTL control. We found that synthetic peptides containing mutations in SIV Gag CM9 and Tat SL8 were no longer recognized by the respective CTL. On the other hand, the described I-to-T replacement at the N-terminal amino acid residue of the SIV Nef IW9 epitope only moderately affected CTL recognition of the variant peptide, TW9. In an attempt to dissect the mechanism of escape of the Nef TW9 mutation, we investigated the effect of this mutation on CTL recognition of CD4(+)T cells infected with an engineered SIV(mac)239 that contained the TW9 mutation in Nef. Although, the wild type and mutant virus both infected and efficiently replicated in rhesus macaque CD4(+)T cells, the TW9 mutant virus failed to induce IFN-gamma expression in an SIV Nef IW9-specific CTL clone. Thus, unlike escape from Gag CM9- or Tat SL8-specfic CTL control presumably by loss of epitope binding, these results point to a defect at the level of processing and/or presentation of the variant TW9 epitope with resultant loss of triggering of the cognate TCR on CTL generated against the wild type peptide. Our data highlight the value of functional assays using virus-infected target cells as opposed to peptide-pulsed APC when assessing relevant escape mutations in CTL epitopes.
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PMID:The Mamu B 17-restricted SIV Nef IW9 to TW9 mutation abrogates correct epitope processing and presentation without loss of replicative fitness. 1832 25

To study the prevalence of oral lesions in HIV infected patients and its relationship with CD4+ cell count in Georgia 732 HIV positive adult patients who were admitted to the Infectious Diseases, AIDS and Clinical Immunology Research Center (IDACIRC) since January, 2006 till October, 2008 were evaluated. Each patient underwent full clinical and standard laboratory examination. CD4+ cell count was determined by the Becton-Dickinson FACSCalibur flow cytometer (MultiTEST CD3 FITC/CD8 PE/CD45 PerCP/CD4 APC Reagent). Socio-demographic data was obtained using a standard questionnaire at the epidemiology department of IDACIRC. Oral manifestations were diagnosed according to EEC clearinghouse classification (1993). Oral lesions were revealed in 546 patients (75%). 186 patients (25%) did not exhibit any oral complications. The prevalence of two or more simultaneously exhibited types of lesions was as follows: three types of lesions were detected in 45 patients (6%) and two types of lesions were detected in 245 patients (33%). The investigation revealed oral candidiasis constituted the most common form of oral lesions, representing a 64% (467 patients), followed by HIV associated periodontal diseases in 216 patients (30%), recurrent aphthous like ulcerations in 118 patients (16%), oral hairy leukoplakia in 58 patients (8%), orolabial herpes simplex infection in 50 patients (7%), human papillomavirus (wart like lesions) in 37 patients (5%) and Kaposi's sarcoma in 3 patients (0.4%). Most of oral lesions cases were found in patients with low CD4+ cell count. Results of this study provide evidence that mucous membrane disorders with HIV infection might serve as an indicator for advanced HIV infection, immunosuppression and decreased CD4 cell counts. The physicians who are taking care of HIV patients have to be familiar with HIV-associated mucocutaneous diseases, their diagnoses, and management.
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PMID:Oral lesions in HIV-positive patients in Georgia. 1912 19

Immunity to the bovine apicomplexan parasite Theileria parva is associated with MHC-I restricted CD8+ T cell responses directed against the intralymphocytic schizont stage of the parasite. A number of schizont-stage antigens that are targets of CD8+ T cell responses from immune animals have been identified but an effective delivery strategy that consistently induces protective CD8+ T cell responses remains to be developed. This study aimed to determine whether fusing Tat, a cell penetrating peptide (CPP) from HIV-1 TAT, to a CD8+ T cell target antigen from T. parva (Tp2) enhances the cytosolic delivery and subsequent stimulation of bovine CD8+ T cell responses in vitro. Using IFN-gamma ELISpot and cytotoxicity assays, it was demonstrated that recombinant Tat-Tp2 fusion protein possessed a superior ability to access MHC-I processing and presentation pathway and to stimulate CD8+ T cell responses compared to recombinant Tp2 protein. Exposure of APC to Tat-Tp2 protein for only 30 min was sufficient for protein uptake and stimulation of CD8+ T cells. This work describes for the first time the utility of a CPP to enhance MHC-I presentation in a veterinary species and supports the evaluation of CPP fusion proteins in the induction of CD8+ T cell responses in vivo.
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PMID:Fusion of a cell penetrating peptide from HIV-1 TAT to the Theileria parva antigen Tp2 enhances the stimulation of bovine CD8+ T cell responses. 1924 7

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